"£10 found in ladies loo on third floor. Come see me if you dropped it." How many times have you received a global email like this at work? Probably quite often, or at least we do here at the Guardian where someone seems to drop a tenner in the building at least twice a week.

But say it was more than £10. Say it was £100 lying on a pavement somewhere – what then?

According to a survey by Alliance & Leicester, four in 10 people say they would hand the cash straight into the police in the hope the owner would try and reclaim it. One in 20 said they would take the money but donate it to charity. But more than half said they would keep the money and use it to cheer themselves up with a meal out or spend it on the family, without feeling guilty about it at all.

So is it a case of finders keepers? Or should you not spend money that doesn't really belong to you?

I was once careless enough to drop my wallet in the middle of Covent Garden and stupid enough not to even notice until a teenage boy who had apparently been running down the street after me tapped me on the shoulder and said, a bit out of breath: "I think this is yours." I was lucky he believed honesty was the best policy – and extremely grateful for it, otherwise I'd have lost all my debit and credit cards and whatever cash was in there at the time. (When I asked if there was anything I could do to say thanks, he asked if I wouldn't mind buying him a milkshake from Ben's Cookies; bless.)

So what would you do if you found £100 on the street? Would you try and track down its rightful owner, or would you be tempted to pocket it as your own? Would where you found the money make a difference, or whether or not it was in a wallet?

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